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In Rechargeable Wireless Sensor Networks (R-WSNs), it is critical for higher data collection rate because sensors have to operate in a very low duty cycle owing to sporadic availability of energy. Therefore, surplus energy of a node can be utilized for strengthening packet delivery efficiency and improving data collection rate for all sensors. In this work, we propose a distributed algorithm to compute...
With the development of Mobile Internet and the rapid growth of mobile social communication and mobile video, the network scale has been growing rapidly and the energy consumption is too huge to be ignored. Current estimates indicate that Information and Communication Technology (ICT) is responsible for a fraction of the global energy consumption ranging between 1% and 2%, among which, the consumption...
Cognitive radio is a promising technology to solve the shortage of spectrum resource. As sensing nodes of the network, secondary users are usually battery powered. Making full use of the energy should also be considered while designing the network. In this paper, we consider the overall throughput of the system and energy consumption. We propose a model of throughput and energy consumption to discuss...
Time synchronization has received a great attention as its crucial parts in wireless sensor networks. To minimize the number of transmission packets and achieve energy efficiency, a time synchronization scheme based on ant colony algorithm (TSAC) is presented in this paper. By exploiting the principle of ant colony algorithm adjusting the pheromone dynamically and automatically, an optimum pair selection...
It is a practical challenge for wireless communication system designs to achieve both high spectral efficiency and energy efficiency because of the nonlinear effect and inefficiency of power amplifier. In previous work, the power amplifier efficiency is always considered as a constant, but it changes with the output power in reality. In this paper, we talk about the impact of variable power amplifier...
In this paper, we present a novel hybrid orthogonal frequency division multiplexing (H-OFDM) for visible light communication (VLC). H-OFDM uses a combination of DC-bias optical OFDM (DCO-OFDM) and asymmetrically clipped optical OFDM (ACO-OFDM) techniques. In this hybrid technique, the absolute value of bipolar DCOOFDM signal is used to carry amplitude information in the first block, while the ACO-OFDM...
In the frequency-limited cellular networks, the underlaying Device-to-Device (D2D) communications is an efficient way to enhance the user access probability and network capacity performance. To satisfy the communication requirements for users in different network sizes, a cooperative transmission strategy based on multi-relay D2D communications is proposed. Specifically, to increase the serving users...
As the energy consumption of network has become an increasingly important issue, traffic grooming on Internet protocol over wavelength division multiplexing (IP-WDM) networks has been widely used for energy-efficient optical network. Traffic grooming can reduce the number of installed light paths and corresponding IP router line cards at the cost of traffic processing overhead. However, traditional...
Wireless Body Area Network (WBAN) is considered as a special type of WSN. It consists of low-power wireless sensor nodes, which are placed on or implanted in the body for continuous health monitoring. MAC protocol is responsible for conflict detection, processing, priority control, timeslot assignment, transmission order etc. So the design of MAC protocol plays an important role in the reliability...
With the anticipated exponentially increasing traffic demand in future mobile networks, energy consumption becomes a significant challenge of the information and communication technology industry. Heterogeneous network (HetNet) is a promising infrastructure for both expenditure and energy saving for cellular operators and has attracted intensive research interest. In HetNets, offloading traffic from...
In multi-user Massive MIMO (M-MIMO) TDD systems, the performance of achievable rates in UL/DL is limited by pilot contamination with the number of BS antennas grows. On the basis of a simplified channel model which allows us to obtain the achievable rates easily, the intercell interference factor is defined as “orthogonality factor” for the first time in this paper. The orthogonality factor is denoted...
In this paper, adaptive power allocation (PA) on the source and relay is investigated to maximize energy efficiency (EE) for OFDMA opportunistic DF links (O2RL). We derive EE function from O2RL model by appropriate definition of variables to represent source/relay PA, subcarrier transmission mode selection (STMS) elegantly. Theoretical analysis demonstrates that EE function for O2RL is strictly quasi-concave...
In order to realize green communication, we consider a cognitive radio network where the secondary user (SU) is equipped with RF energy harvesting capability. The three-state Markov chain is used to model the primary user (PU) channel, which considers both the channel occupation information of the primary network and the channel quality information. We assume that the SU cannot execute RF energy harvesting...
With the development of LTE-A technology, spectrum aggregation, relay and other technologies have been applied to the next generation of wireless communication network. However, current research is mostly focus on only one kind of technology, when these technologies coming together, a lot of prerequisites often have been destroyed, and it becomes difficult to achieve. In this paper, we take spectrum...
Feedback delay often exists in actual communication systems. Relay selection with feedback delay was based on outdated channel state information, which would seriously deteriorate the performance of cooperative communication system. In cooperative system, the best relay is selected to participate in process of information transmission, which can save system power and reduce costs. In this paper, we...
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